A thiol compound having two or more thiol groups in one molecule is useful as a crosslinking agent for a composition containing a rubber and/or a resin such as a halogenated rubber, a halogenated resin, or an epoxy resin.
However, thiol group is a group having an extremely high reactivity, and it reacts with double bond, epoxy group, or other functional group in the rubber or the resin at room temperature in the presence of a catalyst such as a metal oxide or an amine compound. A thiol compound also often undergoes molecular weight increase, for example, by self-oxidation. Accordingly, use of such thiol compound for the crosslinking agent has been associated with the problems of inferior storage stability as well as the risk of reduced work productivity.
In the meanwhile, zinc oxide has been used as a crosslinking agent in the composition containing a rubber and/or a resin.
Use of a zinc oxide, however, has been associated with the problems of rubber scorching as well as inferior heat resistance of the resulting composition.